Method and apparatus for reducing the differential pressure sticking tendency of a drill string
US4428441A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 8, 1981 |
| Grant date | Jan 31, 1984 |
| Priority date | — |
| Expiry date | Jan 8, 2001 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/10
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A method for reducing the sticking tendency of a rotating drill string in its drill cuttings and the surrounding wall cake by constructing the drill string elements, such as the tool joints, drill collars, wear knots, etc. with noncircular cross-sectional shapes. The noncircular shapes may be triangular, square or other higher order multi-faceted shapes, or elliptical, etc. Rotation of the drill string causes a periodic opening to form between the noncircular elements and the cuttings and wall cake which results in a movement of the mass of solids around the noncircular elements to positions away from the drill string, thereby mitigating the tendency of the drill string to differentially stick. Further, hydraulic seals are also likely to be broken by the reciprocating action of the noncircular elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.